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3 years ago

How is an isotope different from the standard form of a chemical element?

Chemistry

2 answers:

fomenos3 years ago

8 0

Answer:

its B :diffrent number of neutrons

Explanation:

velikii [3]3 years ago

4 0

Answer:

The standard form of a chemical element is the natural mixture of several isotopes of the same element, which is atoms with the same number of protons but different number of neutrons, while an isotope is a particular kind of atom with a definite number of neutrons.

Explanation:

A <em>chemical element</em> is a pure substance formed by atoms with the same atomic number (number of protons). This is because it is the number of protons what identifies an element.

For example: oxygen is a chemical element, so oxygen is formed by only atoms of oxygen, and the atomic number of those atoms is 8, because every oxygen atom has 8 protons.

Nevertheless, some atoms of oxygen, may have different number of neutrons. Isotopes are different kind of atoms of the same element, which only differ in the number of neutrons. So, some atoms of oxygen will have 8 neutrons, other 9 neutrons, and other 10 neutrons (those are the stable isotopes of oxygen).

That difference in neutrons, is generally accepted that, does not modifiy substantially the chemical properties of the element, but the mass number. So, the isotopes with more neutrons wil be heavier, and the isotopes with less neutrons will be lighter.

Mass number = number of protons + number of neutrons.

In general a chemical element is formed by a mixutre of isotopes of the same element.

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2. How many moles of hydrogen atoms are there in 154 mL of 0.18 M H2SO4? Write your

katrin [286]

2. 0.05544 moles of hydrogen atom are present in 154 mL 0.18 M solution of H2SO4.

3. 15.2506 heat in Joules is absorbed by 150.0 mL of pure water that is heated from 21.2°C to 45.5°C.

4. 0.75 M is the concentration of Na+ ions in 25.0 mL of 1.50 M NaOH is reacted with 25.0 mL of 1.50 M HCI

Explanation:

Number of moles of H2SO4 can be calculated by the given volume and molarity from the formula:

molarity = $\frac{number of moles}{volume of teh solution}$

number of moles = molarity × volume of the solution of H2SO4

number of moles = 0.18 × 0.154 litres

= 0.02772 moles of H2SO4.

Since 1 mole of H2SO4 contains 2 moles of hydrogen

so, 0.02772 moles of H2SO4 will have x moles

$\frac{1}{2}$ = $\frac{0.0272}{x}$

2 × 0.02772 = x

0.05544 moles of hydrogen atom are present in 154 mL 0.18 M solution of H2SO4.

3. The heat absorbed is calculated from the formula:

ΔH = cp × m × ΔT ( ΔT = change in temperature in Kelvin, m in kg, cp= specific heat of water)

putting the values in formula:

ΔH = 4.184 × 0.15 × ( 318.65-294.35)

= 4.184 × 0.15× 24.3

= 15.2506 Joules of heat is absorbed.

4. The concentration of Na+ ions

the balanced equation is

NaOH + HCl⇒ NaCl + H20

from one mole of NaCl 1 mole of NaCl i.e one 1 mole of Na+ ions is formed.

number of moles of NaOH is calculated by the formula:

Molarity = $\frac{number of moles}{volume of the solution}$

number of moles = 0.025L × 1.50M

= 0.0375 moles of NaOH

so 1 mole of NaOH produces 1 mole of Na= ions

hence, 0.0375 moles produces x moles of Na+ ions

$\frac{1}{1}$ = $\frac{0.0375}{x}$

moles of Na+ is produced.

concentration of NaOH in 50 ml solution because NaOH and HCl of 25 ml reacted.

applying the molarity formula from above

Molarity = $\frac{0.0375}{0.05}$

= 0.75 M

6 0

3 years ago

The tabulated data were collected for this reaction:

erastovalidia [21]

Answer:

ai) Rate law, $Rate = k [CH_3 Cl] [Cl_2]^{0.5}$

aii) Rate constant, k = 1.25

b) Overall order of reaction = 1.5

Explanation:

Equation of Reaction:

$CH_{3} Cl (g) + 3 Cl_2 (g) \rightarrow CCl_4 (g) + 3 HCl (g)$

If $A + B \rightarrow C + D$ , the rate of backward reaction is given by:

$Rate = k [A]^{a} [B]^{b}\\k = \frac{Rate}{ [A]^{a} [B]^{b}}\\k = \frac{Rate}{ [CH_3 Cl]^{a} [Cl_2]^{b}}$

k is constant for all the stages

Using the information provided in lines 1 and 2 of the table:

$0.014 / [0.05]^a [0.05]^b = 00.029/ [0.100]^a [0.05]^b\\0.014 / [0.05]^a [0.05]^b = 00.029/ [2*0.05]^a [0.05]^b\\0.014 / = 0.029/ 2^a\\2^a = 2.07\\a = 1$

Using the information provided in lines 3 and 4 of the table and insering the value of a:

$0.041 / [0.100]^a [0.100]^b = 0.115 / [0.200]^a [0.200]^b\\0.041 / [0.100]^a [0.100]^b = 0.115 / [2 * 0.100]^a [2 * 0.100]^b\\$

$0.041 = 0.115 / [2 ]^a [2]^b\\ \[[2 ]^a [2]^b = 0.115/0.041\\ \[[2 ]^a [2]^b = 2.80\\\[[2 ]^1 [2]^b = 2.80\\\[[2]^b = 1.40\\b = \frac{ln 1.4}{ln 2} \\b = 0.5$

The rate law is: $Rate = k [CH_3 Cl] [Cl_2]^{0.5}$

The rate constant $k = \frac{Rate}{ [CH_3 Cl]^{a} [Cl_2]^{b}}$ then becomes:

$k = 0.014 / ( [0.050] [0.050]^(0.5) )\\k = 1.25$

b) Overall order of reaction = a + b

Overall order of reaction = 1 + 0.5

Overall order of reaction = 1.5

3 0

3 years ago

Why does carbon form so many organic compounds?

11111nata11111 [884]

Because each carbon atom can form for chemical bonds to another’s atoms and because the carbon atom is just the right small size to fit in comfortably as parts of very large molecules

8 0

3 years ago

The total pressure in a tank is filled with a mixture of gases : Oxygen, Helium, and Argon is 15.3 atm. The P(He) = 3.2 atm, P(O

Viktor [21]

Answer:

4.7 atm

Explanation:

From the question given above, the following data were obtained:

Total pressure (P) = 15.3 atm

Pressure of Helium, P(He) = 3.2 atm

Pressure of Oxygen, P(O) = 7.4 atm

Pressure of Argon, P(Ar) =?

The pressure of Argon, P(Ar) in the tank can be obtained as illustrated below:

P = P(He) + P(O) + P(Ar)

15.3 = 3.2 + 7.4 + P(Ar)

15.3 = 10.6 + P(Ar)

Collect like terms

15.3 – 10.6 = P(Ar)

4.7 = P(Ar)

P(Ar) = 4.7 atm

Therefore, the pressure of Argon, P(Ar) in the tank is 4.7 atm

4 0

3 years ago

Say the Tuna is removed from the ocean food web, how would it affect other organisms in the food web?

den301095 [7]

Answer:

removing a top predator may cause its prey to become more abundant, as fewer individuals are eaten. But with more prey around, the organisms that it eats may become scarcer. Seemingly simple changes can have complex effects, with direct and indirect interactions rippling throughout entire ecosystems.

Explanation:

3 0

4 years ago